The effects of phospholipase A (PLA) and phospholipase C (PLC) on bioelectrically excitable tissues have been extensively studied in order to probe the function and structure of membranal phospholipids. In contrast, phospholipase B (PLB; lysophospholipase) has not been studied due to the lack of availability of large amounts of purified enzyme. We have unique access to the oriental hornet venom, which is very rich in PLA and PLB activities. We also are able to obtain the venom of the bald-faced hornet, a resident of western New York, which also contans PLA and PLB activities. The first phase of this program is the isolation and characterization of the PLA and PLB activities from these venoms. Among other properties to be characterized are the antigen structures of the enzymes, since these will offer very precise criteria of purity. Once isolated, the effects of the enzymes on neurological tissue will be examined. These experiments should help clarify the mechanism(s) of convulsions induced by exogenous PL and the role of endogenous PL in convulsive states; essentiality of PL activity of presynaptically active animal toxins; effect of disruption of hydrophobic bonding by PLA plus PLB on permeability and ultrastructure of biological membranes; contribution of PL to the pharmacological actions of the hornet venom.